The present invention relates to cylinders, for example, rodless cylinders, which are used to operate various machines. More particularly, the present invention relates to a cylinder with a speed control mechanism in which a piston is accelerated smoothly at an initiation end of a stroke thereof, or in which the piston is smoothly decelerated at a termination end of a stroke thereof.
Japanese Patent Application Unexamined Publication (KOKAI) No. 7-158614 discloses a rodless cylinder with a speed control mechanism. In the rodless cylinder, a piston is slidably fitted in a cylinder tube, and a head cover is secured to an end of the cylinder tube. A hollow cushion ring is disposed at the end of the cylinder tube such that the cushion ring can be inserted into a hollow portion of the piston. Sinusoidal grooves are formed on the outer surface of the cushion ring. The sinusoidal grooves are formed such that the depth thereof changes sinusoidally with respect to the longitudinal direction of the cushion ring. The sinusoidal grooves are deepest at the cushion approach side of the cushion ring. The rodless cylinder is arranged such that all of the fluid flowing between the inside and outside of the cylinder tube flows through an internal passage in the hollow cushion ring. The conventional rodless cylinder has the function of smoothly accelerating the piston at an initiation end of a stroke thereof, or the function of smoothly decelerating the piston at a termination end of a stroke thereof.